Scaling / Publishing - setting a limit

I have a swf which is 1024x768. It resizes to fit the browser window, which works just fine. However, it contains bitmap images, so while I have no problem with it resizing downwards, I don’t want it to stretch beyond 1024x768, because the bitmaps obviously pixelate.

Is there anyway of setting a limit as to how far it will scale. Or are there any workarounds for this?